Water back for steam generators



J. E. BELL Oct. 6, 1931.

WATER BACK FOR STEAM GENERATORS Filed July 26, 1924 5 Sheets-Sheet l N TL MLU J. E'. BELL WATER BACK FOR STEAM GENERATORS Filed July 26, 1924 Oct. 6, 1931.

5 Sheets-Sheet 3 Oct 6, 1931- .1. E. BELL 1,825,933

'WATER BACK FOR STEAM GENERATORS Filed July 2e, 1924 5 sheets-sheet 4 INVENTOR ATTORNEY Oct. 6, 1931. J. E. BELL 1,825,933

WATER BACK FOR STEAM GENERATORS Filed July 26, 1924 5 Sheets-Sheet l5 E J' E J Zyl@ y iE/E E Y u d $2715, a) Qj/, Jn@

JD Y

JB Jia J E EWE gli# KE H5 K2@ K z H5 z H H J' l5 J /5 w INVENTOR -4- 2 WML/ga@ ATTORNEY K2 Ha H6 Mw a V'HZ f YNITE;

L STATES,

PATENT ,OFFICE f JOHN E. BELL, E BnooKLYN, NEttr Yonx, Assrenon '.roEosTEn .WHEELER consona- Trou, oF NEW YORK, N. Y., A

CORPORATION 0F NEW YORK 'WATER ,BACK Eon, STEAM GENERAToRs Application mea Julyzs,

Themajor object of the present invention is to provide an improved water back or channelled structure lforming a Water cooled lming for the clinker or ash pit of a boiler furnace and incorporated in the water ycirculating system of the boiler, 'and'serving toeliminate or minimize the injurious eifects on the wall of `an ash-pit of high combustion cham- `lower` temperatures, slagand the abrasive action of fuel andashes, and which at the same time desirably and eiiiciently augmente the boiler heating surface, or reduces the amount of such surface otherwise required in a boiler of given capacity.

The use of a water back in the wall of a clinker pit andportions of the combustion chamber walls adj acnt the fuel bed in boiler -furnaces has long been known, and the present tendency to more eilicient combustion, in

`many cases by the'useof preheated air for combustiomfwith a resultant increase in combustion chamber temperaturesabo've those at l has been'attended with certain serious which combustion chamber walls formed of refractories in the usual manner are durable, haveled to attempts to extend water backs to protect portions of the combustion chamber chamber temperatures necessary for high thermal efficiency. In accordance with the 'presentinventiom I form water backs out of conduit elements of the character which have y been developedfor use in' so-called radianty heat superheaters, and in the preferred mode of practicing'my invention I employelements v of the -character disclosed inmy prior Patent No. 1,296',7 39, which are composed of wrought steel tubes enclosed by a relatively massive, vcast metal casing usually formed of perfo rated blocks of cast ironpstrung on the tubes and shrunk inv place thereon. This newuse, of the conduit elements disclosed in my said 1924. Serial No. 728,308.

prior Patent ',No. 1,296,7 39, is attended `with important advantages not attained in the use of such elements in superheating steam, and

an understanding of which may be facilitated by the following explanation:

In a boiler furnace, regardless of the character of the fuel burned, the combustion chamber Walls are inevitably subjected to the alternate action of reducing and oxidizing flames. -Regardless of how much excess air for combustion may be supplied, the exposed surfaces of the combustion chamber walls will be occasionally licked by tongues of flame and bodies of burning gases which are reducing in character, and regardless of how low a percentage ofrexcess air for combustion may be v employed, the same surfaces will be intermittently licked by tongue iames and bodies of burning gas which are highly oxidizing.

In the lcase of radiant heat superheaters, I

have found that as an apparent result of this alternate oxidizing and reducing action, the cast iron casing blocks for the superheater elements in some furnace locations will rapidly deteriorate, the deterioration being largely due to a iaking off ofthe cast iron in akes a sixty-fourth of an inch or so in thickness.

I have discovered, however, that this iaking action does not occur, or at least in a degree seriously objectionable, wheny the cast iron ena cased tubes are used in a Water back owing to the lower temperature at which thewater filled Ielements are maintained. In consequence it is practically feasible to locate the Water backs ofthe special construction de- 85.

scribed, in portions of the furnace wall structure wheresuch water backs are most useful, and Where a superheater ofthe same construetion could not be successfu'll employed.,

Another and important a vantage attained 99 with water backs composed of tubes encased in heavy iron sections as described, for which there is no analogy in the case of a superheater constructed of similar elements, arises ,from the beneficial effect on the water circulation throu h the water backs of the heat;y

the casing. i a Y With an ,ordinary water back formed of storage an temperature equalizingeect of thin walled tubes and located 'in the portion loo of the furnace structurefwhere it is most needed, it is almost impossible from a practical standpoint, to avoid occasional rates of heat absorption in localized portions of the water back which are high enough to produce steam pockets impeding, stopping, or even reversing the water circulation, especially as practical considerations make it necessary to eep the number of connections from the water backs into the boiler drums as small as possible. The formation of a steam pocket in an ordinary thin walled Iwater back is apt to result in destructive overheating of the portion of the water back lled with steam.

With water backs constructed in accordance withthe present invention, steam pockets are not apt to be formed as the result of intermittentand temporary. increases in the heat absorption rate of localizedportions of the Water back because of the heat storage capacity of the casing. In consequence of this eat storage capacity, on a sudden increase in the rate of heat absorption. by any localized portion of the water back, an appreciable portion of the heat then absorbed is utilized in raising the temperature of the casin This tends of itself to reduce the rate of eat absorption, and checks any sudden increase in the rate of heat transfer to the water space surrounded by the casing. Moreover the over heated localized portion of the Water back casing transfers heat by conduction to adjacent portions of the casing as well as to the adjacentv water space. Furthermore, when a steam pocket is formed in a localized portion of the water back, the portion of the water back structure between the steam pocket and the fire is not quickly overheated to the point of destructionbecause of the heat transfer by conduction from said portion to other portions of the water back.

Some of the 'advantages obtained with water backs formed of steel tubes encased in cast iron blocks may be obtained by the use of east steel elements such as are now in use in radiant heat superheaters, but for Water back pur oses elements formed of Wrought steel tu es encased in iron blocks are preferable to cast steel elements, because they are substantially cheaper, and because they do not have the tendency to bow or bend in planes parallel to their length which is characteristic of cast steel elements. The use in water backs of the wrought steel tubes encased in cast iron blocks also facilitates and cheapens the cost of making satisfactory end connections to the elements, and the tubes encased in cast iron may be readily cleaned internally which is necessary in the case -of water backs but not in superheaters. The various features of novelty which characterize my invention are pointed out with particularity -in the claims annexed to and orming apart of this specification. Fora better understanding of the invention however, its advantages and specific ob- -ects attained with its use, reference should e had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred forms of my invention. f

Of the drawings:

Fig. 1 is an elevation in section of a steam generator including elements forming a boiler, a furnace chamberbelow the boiler comprising a` combustion chamber and a stoker and ash or clinker pit below the combustion chamber.

Fig. 2 is a section on the broken line 2-2 of Fig. 1; v

Fig. 3 is a partial section on the line 3-3 of Fig. 1;

Fig. 4 is a' rear elevation of a portion of the steam generator .shown in Fig. 1;

Fig. 5 is a section on the line 5-5 of Fig. 1; Fi 6 is a partial section on thc line 6--6 0f Fig. l; l v

Fig. 7 is an enlarged section of a portion of the apparatus shown in Fig. 1;

Fig. 8 is a section on the line 8 8 of Fig. 7;

Fig-9 is an elevation withparts broken away and in section of a modified construction;

Fig. 1() is a view taken similarly to Fig. 9 illustrating a second modification;

Fig. 11'is a partial rear elevation lof the portion of the boiler shown in Fig. 10;

Fig. 12 is a diagrammatic elevation of a. portion of a steam generator in which the radiant heat absorbing elements incorporated in one wall are divided into two separatel sets arranged one above another;

Fig. 18 isa view taken similarly to Fig. 12 illustrating another mode of connecting two water back sections into the boiler circulatino' system;

ig. 14 is a partial rear elevation ofthe construction shown in Fig. 13;

Figs. l5 and 16 are views taken similarly to Figs. 13 and 14, respectively, illustrating a third connection arrangement; and

Figs. 17 and 18 are views taken similarly ito Figs. 13 and 14, respectively, illustrating still another connection arrangement.

In the drawings andl referring lirst to the construction shown in Figs. 1 to 6, A represents the combustion chamber of a steam generator at the upper end of which is located a water tube boiler comprising the usual Wa ter and steam containing elements. In lthe conventional form illustrated, the boiler proper is of the so called horizontal water tube cross drum type, the inclined water tubes B being connected at their ends intofront and rear headers C and D; The headers C are connected by elongated nipples into the steam and water drum E and the upper ends l of the rear headers D are connected to the rear of the drum E by horizontal circulating tubes F. In the construction shown, the boiler steam pipe leads from the drum E to the top inlet header Gr of a radiant heat superheater comprising elements G connected be-i patented April 28, 1931, Patent N o. 1,802,456.

ln accordance with the present invention, provisions now to be described are made for cooling the side walls and the lower portion of the rear wall of the combustion chamber A. The pro-visions illustrated for cooling the side walls of the combustion chamber comprise a series 'of tubular elements I advantageously inclined at or about the same angle f -to Lthe horizontal as the water tubes B. As

' shownin Figs. 2 and 5, each tubular element l comprisesan inner tube z' and a sectional casing therefor which may be formed of perforated blocks of cast iron. The casing sections are rectangular in outline and the vay I rious casingsectlons for the elements I 1n each sidfe wall unite to form a smooth inner heat absorbing surface. rlhe lower ends ofthe bare tubes z' at the front of the boiler are out-turned and connected into a corresponding vertical inlet header H.- Each-header H is connected at its upper end tothe lower ortion of the drum lE throughl the tubes As shown, the upper end of'each header H is bent over and extends horizontally and the tubes H which are also bent have their end portions connected to the header extending transversely away from the latter,l this arrangement permitting the thermal expansion and contraction ofthe parts without subjecting them to undue strain. At the rear of the boiler the ends df the bare tubes z' extend through the furnace housing wall and are secured into corresponding vertical headers J. Each header J is connected at its header isV intended to be connected to the ,heaters now in use.

drum E byo four tubes J The elements I are supported and held in alignment by connections from a plurality of the casing sections of each element to supporting frame members, but this need notV be illustrated and described in detail herein as this structure is similar in this respect to'radignt heat super- Incorporated in the rear radiant heat superheater,;G and extending `wan below Y the* as that of the lower end of the inclined upper surface of the stoker X and substantially coextensive with the vertical extent of the ash or clinker pit X2 is a water back K composed of vertical elements each comprising a bare tube K having out-turned horizontal extending end portions connected into the lower and upper horizontal headers K2 and K3, respectively, of the Wat'erback.'v The body portions of the bare tubesare encased in blocks of cast iron similar to those employed in the elements I. The headers` K2I and Ks are sup-v y ported on brackets which may be secured to .columns or buckstays forimng a part of metallic frame work of the 'boilerhousing In the construction illustrated in Figs. 1 to 6,

the waterback K is connected into the boilerl circulating system through the headers Hand J the lower inlet header K2 of the waterbackl being connected at each end to the lower end of the corresponding header H by a horizontal pipe H2. The upper outlet header K3 of the waterback K is connected to the lower end of the adjacent header J through a horizontal nipple or'pipe connection K5. Suitable pro-l vls'ions are required to accommodate the thermal elongation and contraction of the body portions of the Water back elements Without ments of said body portions. and' without creating objectionable stresses, and strains in the elements and their connections linto the boiler circulatin housing and wit out giving rise to air leak-y through the latter. f The manner in A,permitting undue warping or bending movelas system, or in the boiler w ich these results are obtained with respect tot-he water back K is illustrated in Fi 1, 7

and 8. As shown in the lastmentioned gures, Y

a special cast metal elbow )casing K* is pro-A vided at each end of the vertical body portion of each tubular element. The elbow portion vof each bare end of each tube K passes through a corresponding casing K suitable refractory material in the form of til bricksKVbeing mounted in the casing K* in front of the otherwise exposed elbow portion of the bare end of the tube K; As shown the open inner side of the casing K* is undercut to es or lire hold the refractory material K7 in place.

The horizontal portion ot the bare tube K passessnugly through a whole case Ke formed for the purpose in the outer end of the elbow" casing.v "The ortions of the bare tubes K at the outer ends of the elbow casings K* pass throu h a cellular honey-comb like structure K o cast metal parts incorporated in the The spaces about the-bare.

housing wall. tubes K in the channels thus provided, may advantageously be packed with Sil-o-cel or like material which preventsheat radiation losses and prevents air leakage through the channel without interfering with the bending and bodily up and down movements of the A y l transverse end portions of the tubes K necesdownward from approximately the same level sary asthe body portions of the tubes .K

thermally elongate and contract, to avoid subjecting the elements or their connections to to stiffening and aligning metallic members lo' K at the rear ofthe elements K and'separated from the latter by suitableheat insulating material K1".

With the described arrangement of the side and rear wall waterbacks and the super heater, the side walls and rear `wall are largely lined by metallic heat absorbing heat apparatus, thus directly cooling these walls and indirectly cooling and protecting the front wall of the combustion chamber partly by lowering the temperature in the com.'

bustion chamber and partly by the obsorption of radiant heat from the front wall of the combustion chamber. This cooling of the combustion chamber walls is a matter of great practical importancefasthe modern tendency to more eicient combustion with a relatively low amount of excess air and with that air preheated in many instances tends to the production of furnace chamber temperatures high enough to etect a rapid destruction of fire brick furnace walls. By abstracting heat from the combustion chamber with water backs incorporated in the combustion chamber walls as'described herein, the most eilicient combustion practically obtainable may be maintained without overheating the4 combustion chamber walls. While the heat which they absorb from the combustion chamber lowers the temperature of the furnace gases and decreases the amount of heat available I'or recovery by the ordinary boiler water tubes, the water backs and the radiant'heat suY rheaters G form highly etiicient heat 'absor ing devices, and their use permits of a reduction inthe total boiler heating and superheating surface otherwise required for a given steam generatin and superheatin capacity.

he water back il ustratd in Figs. 1 to 6 is characterized by the simplicity and effectiveness of the means of connection into the water circulating system of the boiler proper and the supply thereto of water at the rapid rate required to keep the water back elements filled with water notwithstanding their ra id absorption of heat. It will be observe that notwithstanding the compara- 'tive simplicity of the pipe connections between the water elements and the boiler system proper, good advantage is taken of the circulation producing eiect resulting from the di'erence in density of the water supplied through the down-comers H to the water elements and the ascending column of water 1n the risers J which is lighter both because l' the Water is hotter and also because of entrained steam bubbles. `:Lt is especially to be noted that the down-comers H by virtue of their shape and disposition may readily be made of ample size to insure an adequate supply of water Vto the lower ends of the elements of the water back K as well as to the lower ends of the elements I. Furthermore, the character of the connections shown in Figs. l to 6, as well as in the' other forms of the inventionillustrated, permit of the ready use of the invention withexisting types of boilers, and make it possible to provide existing boiler furnace installations with water backs at a minimum of expense and trouble. The length of the horizontal tubes J', and the' connectlon of the bent tubes H to the horizontally turned upper end of the down-comer H provide the iiexibility required to accommodate thermal expansion and contraction in boiler and water backs. s

Water backs composed of wrought steel tubes encased in cast iron blocks, as described,

possess special advantages over water backs heretofore constructed in addition to the important advantages to which reference has already been made. As a result of the flexibility of the steel inner tubes and the rel,- tively short length of the individual casing blocks, thermalexpansion and contraction has small tendency to destroy the elements, and, in consequence, the elements unite to provide a heat absorbing surface which is smooth'enough to minimize the adherence of slag and ashes and to facilitate the cleaning of the surface when this is necessary. Furthermore, the massive character ofthe casing blocks renders them immune to injury by the impingement of bars or other tools used in removing adhering slag. It will be apparent, ,of course, that should conditions of' use result in surface injury to the casing blocks,"much such surface deterioration may occur without appreciable reduction in the eifectiveness of the Water back. While the loint between the Ytubes and the casing locks offers resistance to the flow of heat from the casing blocks into the tubes, this is not especially objectionable from any point of View', because this resistance is never sufficient toprevent the rate at which heat is taken up by the water from being rapid enough to make the element an extremely efficient portion of the boiler heating surface. Moreover the reduction in effective heat ab-` sorption caused by this point resistance tends to the avoidance of ditliculties in maintainin a proper water circulation. The use of an e fective water back immediately adjacent the fuel bed is es eciall advantageous because of the slag coo in e ect, which prevents any such serious resu ts from slag adherence to the furnace walls as is a common source of annoyance and injury to ordinary fire brick walls, particularly when the furnace is pro vided with a mechanical Stoker which is intermittently operated.

The use of the invention makes it readily possible to extend the water back K at the rear of the Stoker downward as ar as may be required to eifectually cool the slag and ashes passing to the ash removing means and to protect the latter as well as the adjacent portion of the stoker mechanism against overheating by absorbing radiation heat therefrom. As conventionally illustrated in Fig. 1 the ash removing means comprise the customary clinker grinder rolls X located at the bottom of the clinker pit X2. It will be readily apparent that a water back maybe used at therear of the Stoker in cases where it is not desirable to employ the water backs.

' I, or where if the latter be used it isdesirable to separately connect the water backs into the boiler system. In such a case the Water back AK may advantageously have its water back header K3 connected to the steam and water A drum E by means of tubes J alongside the circulating tubes F, and external vertical riser pipes JA as shown in Fig. 9. Fig. 10 illustrates a form ofywater back KA which may advantageously be employed in,

some casesparticularly in the rear wall of a combustion chamber not provided with a radiant heat superheater as in the construction shown in Figs. 1 to 8. The waterback KA- diiers rom the water back K first described primarily in thefact that the vertiv `cally disposed vbody portions of the tubes K are vertically. elongated so that the upper water back header K3 of Fig. 10 is located at about the same level as the uppersuper= heater header G in Fig. 1. The upper portions ,of thevertically disposed parts of the tubes K in the particular arrangement shown in Fig. 10 are not surrounded by casing blocks of cast metal but are directly exposed to the interior of the combustion chamber. The

' reduction in radiant heat absorbing surface The take-ofi pipes J 5, are connectedinto the water drum E throughV headers J 5 at the side edges of the rear end of the boiler and cor'- responding horizontally disposed circulating tubes J -It will be seen that in both the structures shown in Fig. l and Fig. 10 the water Wall is positioned and has'sufficient ver- .tical lextent to rovide a water wall surface for substantialiny the vertical extent of the ash pit.

In some cases it is desirable to reduce the length of water back elements incorporated in a single combustion chamber wall by employing a plurality lof Kwater back sections shown for example in Figs. 13 to 18. The water back sections K and KB shown in those figs., are, separately considered, similar in construction to the water back K previously described, the water'back section KB bein located above the water back section K. As s own in Fi 12, the out-turned upper end of the bare tu e portions of the water back section K and the lower opt-turned ends of the bare tubes of the upper water back section KB are connected by an external header K23. AS shownin Figs. 13 and 14 water is supplied to the inlet header K2 of the water back header K throuoh branches H2' from down-comers HA whisli may be similar` in their arrangement and in their conf nections to the water drum E, to the downcomers H previously described. The inlet header K2o of the water back section- KB is supplied with water from the down-comer pipes HA by branch pipes H20. The outlet headers K2 and K30 of the water back sections KB and K are separately connected at their ends to the steam and water drum by means of individual risers JA and JB, respectively, each ofwhich may be similar to the riser JA of Fi 9 and be similarly connected by tubes'J to the drum E. With this arrangement the two water back sections K and ICB are connected in parallel so to Speak, between the common down-comers HA and the steam and water drum.

In the arra ement shown in Figs. 15 and 16, the water ow throu h the elements of the water back section and KB is in parallel asin Figs. 13 and 14, but in lieu of the separate risers JB for the water back section KB, the outlet header Kso of the lat,-

ter is connected at its ends by bent i es J1"A into the risers JA. Except for this i erence the arrangement shown in Figs. 15 and 16 is the same as that shown in Figs. 13 and 14. The arrangement shown in Figs. 17 and 18 diers from that sho'wn inl Figs. 13 and 14 in the omission of the risers JA and by the addition of bent pipes J15 connecting the ends of the outlet header K2 of the water back section K to the ends of the inlet header K2 of the water back section KB, so that with this arrangement the water passes in series first through the elements of the water back section K and then throllh the elements in the water back section It willbe observed that in most of the` y forms of water back constructions illustrated, the water back conduit elements, the Structural sup 'orting frame members at the outer sides o said-elements, and the heat insulating material at the outer side of the elements, form a unitary kfurnace wall section. Novel features ofconstruction and arrangement pertaining to the sectional water headers illustrated in Figs. 10 to 18 not specically claimed herein, are claimed in my divisional application Serial No. 83,7 89, filed January 6, 1926, Pat. No. 1,666,483, granted A ril 17, 1928.

%Vhile in accordance with the provisions of the statutes I have illustrated and described the best forms of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention and that certain features of my invention may sometimes be used with advantagev without a corresponding use of other` 'features. e

Having now described my invention what I claim as new and desire to secure by Let-ters Patent, is:

1. A steam4 enerator comprising elements forming a boi er, wall structure enclosing a combustion chamber, stoker apparatus within said wallstructure, and defining the lower extent of the combustion chamber, said wall structure extending below the combustion chamber and providing an ash pit and including a water wall positioned to be contacted by residue resulting from burning of fuel on the Stoker, said water wall being positioned and having sufficient vertical extent to provide a water wall surface for substantially the vertical extent of the ash pit, an upper horizontally disposed header for said water wall outside said wall structure, a lower horizontall disposed header forvsaidl water wall outsi esaid wall structure, said water wall comprising tubes having vertically extending heat absorbing portions and end portions extending through the wall structure and connected to the upper and lower horizontally disposed headers outside said Wall structure and metal blocks contacting the vertical heat absorbing portions of the water wall tubes and having smooth exposed faces v:forming a substantially smooth continuous p inside wall surface of the ash pit for contact with said residue and transmitting heat from the residue to the water wall tubes, a downflow conduit connecting the boiler with the lower horizontal header, an uplow conduit connecting the upper horizontal header with the boiler, and the vertical extent of the heat absorbing portions of the water wall tubes being sufficient to induce gravity circulation therethrough due to heat supplied to said vertically extending heat absorbing portions.

2. In a steam generator comprising a water tube boiler and a furnace chamber beneath 1t, the improvement which consists in a water back lining for a portion of the furnace `chamber wall composed of verticaletubular elements located at the inner side of said wall and transverse end connections passing through said wall, inlet and outlet headers to which the lower and upper end connections are respectively connected and a separate connection between each end of each header and the boiler proper for maintaining a gravity circulation of water through said elements.

3. A water back element comprising a tube having a body portion and end portions transverse to the body portion and adapted to extend through the wall of a furnace chamber lined by the body portion of the element, perforated casing blocks strung on the body ortion of the element and a cast metal casing for the elbow portion of the tube open at the furnace chamber side of the latter, and provisions for holdin refractory heat insulating material in said opening.

4. A water back element comprising a tube having a body portion surrounded by a metallic casing and an end portion extending transversely to the body portion and adapted to pass through a furnace wall, a cast metal casing section for the adjacent portions of the body and end portions of the tube, said casing section being open at the furnace side of the element and adapted to hold a refractory heat insulating shield in front of said end portion.

5. In a steam generator comprising a water tube boiler of a cross drum type and a combustion chamber beneath the boiler, the improvement which consists in'water backs in the side walls of the generator and a water back in the rear wall of the generator, the rear wall water back being composed of vertical tubular elements with horizontal headers connected to the'lower and upper ends of the elements and the side wall water back being composed of tubular elements inclined to the horizontal and vertical inlet and outlet headers to which the lower and upper ends of the inclined tubes are connected, a connection between the upper end of each of said vertical inlet headers and the steam and water drum of the boiler, a connection between the lower ends of the vertical inlet headers and the inlet header of the rear walli'water back, connections between the outlet header of the rear -wall water back and said/ vertical outlet,

headers, and tubes alongside the boiler circulator tubes between the last mentioned headers and the steam andwater drum.

6. Ina steam generator-comprising a water tube boiler and a furnace chamber, the improvement which consists of vertically disposed elements formin a lining for a portion of the chamber Wa land connections between the boiler and'said tubes for maintaining a gravity circulation of water through the latter, said connections comprising au inlet header connected to the lower ends of said elements and a downcomer pipe having its lower end connected to said header and having a transversely extending upperv end portion and a plurality of pipes transverse t0- iao IDO

ieeneee necting seici end portion to the toiier. 'i e steein generator comprising e weten tube 1noiier anni e, urnme chamber beneath the boiier, the improvement which consists in e ioeck lining 'for e vertically extended portion of e chamber Weii composed c? yerticei tubular eiernents at the inner side oi seid Weil and en outlet header to which tne upper ends of said elements are connected, l

i@ end connections between the Water back and `he boiier for maintaining e. gravity circulation of Water through said elements, said connections including e plurality of outlets ircni seid header distributed?- along the length 3 5 of the netter and conduits connected thereto d extending into proximity with the sides oi combustion chamber extending transyerseiy to seid neeciei's.

ooiier and e, 'turna-ce chamber beneath i" e improvement which consists in a, water iii" fr `for e portion of the furnace chamoinposeei of Vertical tubular eles ioceteii tlieinnei1 side oiD sei vieil transverse end connections passing ingii Weiiig inlet and outlet headers i and ripper end connections connected and e plurality of con ections between. each heacier 'and per for maintaining a gravity "te tei tiinongii seni elements.

e steam boiler navieten drinn, e furnace cnamcia Weten tunes vertically erciinniberso es to receive raeiioni, downteke and uptake Ween sei tubes and boier i downto-ine connection comprising a,

the ooiier setting, and e piuty spaced nipples connecting the upper gned et en York city in the county of Y end of New York this 15th f A. JH-N BELL.

L in n steein generator comprising e Water di of seid. confiait to the Water space of the 

